The double perovskite Sr2FeCoO6 oxide powder has been prepared by nitrate-citrate gel-combustion process for different ratios of citric acid and metals under various pH values and calcined at 700 oC for the complete decomposition of the carbonaceous residues. The effect of pH on crystal development and ionic state of iron has been determined by X-ray diffraction and Mössbauer spectroscopic studies. The analysis revealed that calcinated powder is a single phase cubic perveoskite structure SrFe0.5Co0.5O3 with space group Pm3m and lattice parameter 3.867 Å. Mössbauer spectroscopic results indicate that as-synthesized and calcined samples have mixed ionic states like Fe3+, Fe3.5+ and Fe4+ in the tetrahedral framework of SrFe0.5Co0.5O3.

Keywords: Gel-combustion, Perovskite oxide, X-ray diffraction, Mössbauer spectroscopy.